A reinforcing bar binder is provided with a binding line feed mechanism for feeding out a binding line of a wire or the like wound around a reel to wind around reinforcing bars, a grasp mechanism for grasping the binding line wound around the reinforcing bars and a binding line twist mechanism for twisting the binding line by driving to rotate the grasp mechanism and carries out winding operation of 1 cycle by successively operating the binding line feed mechanism, the grasp mechanism and the binding line twist mechanism.
When a nose in a circular arc shape of the reinforcing bar binder is hung around the reinforcing bars and a trigger lever is pulled, the binding line is fed out along an inner peripheral face of the nose by the binding line feed mechanism to form a binding line loop at a surrounding of the reinforcing bars, a rear end of the binding line loop is cut by a pivoting type cutter blade provided at a binding line feed path, a pair of hook type hooks of the binding line grasp mechanism are closed to grasp the binding line loop and thereafter, the hooks are driven to rotate by the binding line twist mechanism to twist the binding line to bind the reinforcing bars.
However, when the hooks of the binding line twist mechanism grasp to twist the binding line which is loosely wound around the reinforcing bars, owing to a structure of rotating the hooks at a constant position or rotating the hooks while moving forward, there is a case of twisting the binding line in a state in which tension is not applied thereto and in such a case, there is a case in which the binding line loop after binding is not brought into close contact with the reinforcing bars and binding cannot be carried out solidly. Hence, there poses a technical problem to be resolved in order to stabilize the binding strength of the reinforcing bars and it is a first object of the invention to resolve the above-described problem.
Further, the reinforcing bar binder of the prior art is constituted to catch a middle portion of the binding line loop remote from a front end thereof and the rear end by the pair of hooks and this is because when a portion of the binding line proximate to the front end or the rear end is caught, in rotating the hooks, the front end or the rear end of the binding line is drawn out from the hooks to loosen the loop and binding cannot be carried out. Therefore, lengths of a front end portion and a rear end portion of the binding line extended from the portion of the binding line grasped and twisted by the hooks are prolonged, the portions are projected at the surrounding of the reinforcing bars to bring about a drawback that when concrete is cast, the binding line may be projected from a surface of the concrete and an amount of consuming the binding line is large.
Hence, there poses a technical problem to be resolved in order to improve binding finish by making an extra portion projected from the twisted portion of the binding line as less as possible and it is a second object of the invention to resolve the above-described problem.
Further, according to the binding line feed mechanism of the reinforcing bar binding of the prior art, a driven gear with a V-groove is brought in mesh with a drive gear with a V-groove driven by a feed motor, the driven gear with the V-groove is attached to one end of a lever and the driven gear with the V-groove is brought into elastic contact with the drive gear with the V-groove by a spring interposed at the lever. When the binding line of a wire or the like is passed into the V-grooves of the two gears with the V-grooves, the binding line is pinched by the pair of gears with the V-grooves brought in mesh with each other and the binding line is fed to a nose of the reinforcing bar binder by rotating the feed motor.
According to the binding line feed mechanism of the reinforcing bar binder of the prior art in which the driven gear with the V-groove is brought into elastic contact with a single piece of the drive gear with the V-groove by the spring, when linearity of the binding line wound around the binding line reel is poor and a shift in a left and right direction is large relative to a moving forward direction, there is a case in which the driven gear with the V-groove is pressed in a lateral direction by the binding line to disengage from being brought in mesh with the drive gear with the V-groove and a failure in feeding the binding line is brought about. When a predetermined length of the binding line is not fed, a failure in binding is brought about in a twisting step, binding operation is obliged to carry out again and also the biding line is wasted. Hence, there poses a technical problem to be resolved in order to prevent a failure in feeding from being brought about by promoting stability of feeding the binding line and it is a third object of the invention to resolve the above-described problem.